1. Field of the Invention
The present invention relates to a water stop structure and a method of forming a water stop section and is particularly designed to prevent water penetration into an electronic control unit from wires of a wire harness via a connector connecting portion in the wire harness connected a connector of the electronic control circuit.
2. Description of the Related Art
In the case of arranging a wire harness along a water susceptible area in a vehicle such as an automotive vehicle or a motorcycle, a connector connecting portion between the wire harness and an electronic control circuit installed in the vehicle needs to be so designed as to prevent water penetration from wires of the wire harness to the electronic control circuit.
At this time, even if an arrangement path of the wire harness is set in an area not subject to water, water might penetrate to the wires from a water-stop treated portion to the connector connecting portion with the electronic control circuit even if a water stop treatment is applied in an intermediate area of the wire harness in the case where the electronic control circuit is installed in an engine compartment or the like which is a water susceptible area.
Thus, a waterproof connector in which waterproof rubber rings are mounted on respective wires has been conventionally used in a connector connecting portion between an electronic control circuit and a wire harness, whereby water penetration into the electronic control circuit is prevented by a watertight structure of the waterproof connector even if water splashes from outside.
However, if a coated portion of the wire is damaged and a part thereof is peeled off, a crack may reach a conductor of the wire. If this damaged portion is located in a water susceptible area, water reaches the conductor through the damaged portion and penetrates into clearances between strands constituting the conductor. The water having penetrated might possibly penetrate into the electronic control circuit via a terminal crimping portion of the connector through the clearances between the strands by a capillary phenomenon.
Even if a connector connected with an electronic control circuit is a waterproof connector, wires of a wire harness connected with the waterproof connector may have other ends thereof connected to other wires via a non-waterproof connector. In this case, if a connecting portion by the non-waterproof proof connector is subject to water, water might possibly penetrate to conductors of the wires exposed in the non-waterproof connector and further enter clearances between strands of the conductors and reach a connecting portion with the electronic control circuit by the capillary phenomenon similar to the above. Therefore, the wires connected to the electronic control circuit need to have the other ends thereof also connected with the other wires using a waterproof connector.
However, since the waterproof connector is larger as compared with the non-waterproof connector, a larger installation space has to be ensured, which makes it difficult to ensure a wire harness arrangement path in many cases. In addition, the waterproof connector has a higher cost as compared with the non-waterproof connector.
As a connector designed to be waterproof without using the above waterproof rubber rings, the present applicant proposed a waterproof connector, in which a waterproof member made of a material mainly containing a silicone gel is provided and mounted on a terminal insertion side surface of a connector 101, a spacer 102 is arranged on an outer surface of the waterproof member 100 and held onto the connector 101 by a holder 103 as shown in FIG. 9, in Japanese Unexamined Patent Publication No. 2000-144099.
In this waterproof connector, the waterproof member 100 is formed with terminal holes, through which terminals 104 crimped and connected to wire ends are passed through.
The above waterproof connector requires the waterproof member, the spacer and the holder, leading to an increase in the number of parts, a larger size and a cost increase of the connector. In addition, if water reaches the terminal fittings passed through the terminal holes of the waterproof member via conductors of wires by the capillary phenomenon as described above, water penetration to an electronic control unit might not be reliably prevented.
The present invention was developed in view of the above problems and an object thereof is to prevent water penetration without using a waterproof connector as a connector of an electronic control circuit to prevent water penetration to a connector connecting portion with the electronic control circuit, which is installed in a water-free area and no water splashes thereon, from wires of a wire harness connected with a connector.